DESCRIPTION: (Applicant's Description) Epstein-Barr virus is one of a limited number of viruses associated with human cancers and has a high degree of association with one of the three largest groups of AIDS-related malignancies. The ability of EBV to transform primary B lymphocytes is likely to play a role in the development of these malignancies. The objective is to determine the cellular pathways targeted by one of the six viral proteins demonstrated to be essential for transformation, EBNA-3A, that the applicant s preliminary evidence suggests functions as a transcription factor. Specifically, the applicant proposes to: 1) Identify the function of EBNA-3A associated proteins. Preliminary data demonstrates that EBNA-3A associates with at least two cellular proteins, one of which is the J-kappa transcription factor. The unknown EBNA-3A-associated protein(s) will be identified using the yeast two-hybrid system. 2) Identify cellular genes regulated by EBNA-3A. The preliminary data, as well as homology to other viral proteins, suggests that EBNA-3A is highly likely to function as a transcriptional regulator, affecting expression of cellular genes that contribute to EBV-mediated transformation. EBNA-3A-regulated genes will be identified by representational difference analysis. 3) Determine the significance of EBNA-3A function within the context of viral infection. Lastly, the applicant will determine the significance of those EBNA-3A functions that have already been identified, as well as those to be identified in this application, by generating recombinant EBV encoding EBNA-3A with mutations affecting each individual function. By examining the ability of these recombinant EBV genomes to immortalize primary human B lymphocytes, the applicant will determine whether a given function contributes to EBV-mediated transformation. Identification of EBNA-3A-associated proteins and EBNA-3A regulated genes will enable determination of the cellular pathways targeted by EBNA-3A. Analysis of these pathways, using EBNA-3A as a probe, is highly likely to not only further the understanding of EBV- associated malignancies, but also increase the knowledge of the control of cellular proliferation that may be disrupted in other types of cancers.